Traditional telephony can be difficult or impossible for persons who are who are deaf, hard of hearing, or speech-impaired (D-HOH-SI). Communication by telephone requires each party to a telephone call to be able to hear and/or speak to the other party on the call with sufficient fidelity to communicate. For hearing or speech impaired persons, audio communication with sufficient fidelity is difficult or impossible, making telephone communication difficult or impossible.
Early approaches to facilitating telecommunications for D-HOH-SI persons included text-based telecommunications relay service (TRS). Text-based TRS services allow a D-HOH-SI person to communicate with other people over an existing telecommunications network using devices capable of transmitting and receiving text characters over the telecommunications network. Such devices include the telecommunications device for the deaf (TDD) and the teletypewriter (TTY). Text-based TRS services were well-suited to the bandwidth limitations of subscriber lines of the time. The bandwidth limitations of subscriber lines were also a limiting factor in the widespread use of video telephony.
The availability of affordable, high-speed packet-switched communications has led to the growth in the use of Video Relay Service (VRS) communication by D-HOH-SI persons. Using VRS equipment, D-HOH-SI persons may place video calls to communicate between themselves and hearing individuals (non-D-HOH-SI) using sign language (SL). VRS equipment enables D-HOH-SI persons to talk to hearing individuals via a sign language interpreter (SLI), who uses a conventional telephone at the same time to communicate with the party or parties with whom the D-HOH-SI person wants to communicate.
Direct Video Calling (DVC) is an emerging telecommunications service for one-to-one video communication provided by a call center that allows conversations to occur between two participants in a call using American Sign Language (ASL) without the need for translation services. DVC is a support service that enables customer service representatives who know American Sign Language (ASL) to communicate directly with D-HOH-SI people who rely on ASL as their primary language without the need for an intermediary to relay these conversations. With DVC, a D-HOH-SI person can use ASL and a videophone with a real-time video connection to make a call directly to an ASL-trained agent within a call center. DVC solutions have been adopted by a variety of government agencies and private corporations, and the number continues to grow.